Fuel systems for motor vehicles are known to include a fuel tank and a filler tube through which fuel is dispensed into the tank. It is known to use a removable threaded cap at the end of the filler tube to close the tube. The threaded fuel cap is the primary seal for the fuel system on most domestic vehicles. For the threaded cap to seal the fuel system properly, the cap must be twisted on correctly. If a fuel cap is not properly tightened, is missing or is defective, a significant amount of fuel can be released to the atmosphere through evaporation from the fuel tank.
It is known to use a movable damper and a rubber seal to close the fuel system, either as the primary shut-off valve or as a secondary, supplemental shut-off. A known assembly of this type includes a metal tube or sleeve and a plastic insert or cover adapted to be received within the sleeve. An annular groove is provided on the outer surface of the plastic insert, and a rubber seal or the like is positioned within the groove between the inner surface of the metal sleeve and the outer surface of the plastic insert. Properly functioning, an assembly of this type can be effective in minimizing the loss of fuel from the fuel system. However, through age, fatigue and deterioration of the seal and associated components, the sealed area between the insert and the outer sleeve provides a path for the leakage of vapors from the tank. Even a small leak can result in significant loss of fuel and environmental pollution.
It is known also to use a positive sealing insert in the end of the filler tube and a capless refueling closure unit at the end of the filler tube. Known capless refueling systems are complex and costly. Assembly of such a system can be difficult and time consuming.
What is needed in the art is a vehicle fuel system filler assembly that includes an effective shut-off valve assembly with reduced area of potential leakage together with an outer closure therefore that can be assembled quickly, easily and securely.